1. Field of the Invention
This invention relates to investment molding and in particular to the forming of mold assemblies for use in the investment molding process.
2. Description of the Prior Art
In the investment molding process, the article to be cast is first produced as a wax pattern. Conventionally, the pattern may be dipped in a ceramic slurry to form a ceramic shell around the wax pattern. Subsequently, the wax is removed from the set shell to leave a cavity accurately corresponding to the wax pattern which thereby defines the desired casting mold.
It is desirable to form a plurality of such molds in an assembly for mass production of the article.
As shown in U.S. Pat. No. 3,854,832, of Glenn Sherwin Cowper, which patent is owned by the assignee hereof, a handling rod may be utilized for supporting the pattern as during the coating process. It is conventional to build up the coating by repeated dipping thereof into a suitable coating slurry, such as a ceramic slurry. Sand may be applied to each coating before applying the next coating to build up body in the mold. Conventionally, up to ten such coatings may be applied to form the desired mold.
The molds are then dried and delivered to a suitable autoclave for melting the wax from the surrounding set ceramic coating. The molds are completed by a flash firing in a furnace at approximately 1800.degree. F. which effects a curing thereof. The castings are then made in the mold cavities by introduction of suitable molten metal after preheating the cavities to a suitable temperature. Upon completion of the setting of the metal, the ceramic coating is vibrated to break it free from the metal casting and permit final treatment of the casting which may include blasting and salt solution treatment and removal of the gates as by grinding.